Decade bandwidth amplification at microwave frequencies

The concept and the advantages of distributed amplification are considered. An approach suitable for obtaining wideband gain at microwave frequencies makes use of GaAs FETs as the active elements. The resulting amplifier is truly distributed in the sense that its gate and drain lines become microstrip transmission lines with a number of FETs connected between them. In this form the obtained structure can more appropriately be called a traveling-wave amplifier. Attention is given to a simplified equivalent-circuit diagram of a FET traveling-wave amplifier, a schematic illustration of signal paths and their respective phases, modified traveling-wave amplifier topology for increased power amplification, four separate power-limiting mechanisms in microwave traveling-wave power amplifiers, and the demonstration of significant power and gain capabilities over decade bandwidths.